Soda and lime are added to glass batch in the form of soda ash (Na2CO3) and limestone (CaCO3). During heating, these two ingredients decompose to give off carbon dioxide (CO2), the resulting products being soda and lime. Compute the weight of soda ash and limestone that must be added to 170 lbm of quartz (SiO2) to yield a glass of composition 75 wt% SiO2, 18 wt% Na2O, and 7 wt% CaO.